H1000 old lot vs new lot.

entoptics

entoptics

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Joined
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Thought I'd throw this out there as a friendly reminder, as well as some actual data to demonstrate what most of us already know.

Got 5 lbs of H1000 a couple months ago, and finally got out to test it against the remainders of an 8lb jug I bought a couple years ago.

Used the exact same 264 Win Mag load for both, loaded together in one session, and shot together in the same gun/session...

60.99 grains
129 gr SST
Fire forming new Winchester brass, bullet jammed ~0.020

New Lot
2965 fps

Old lot
3049 fps

That's an 84 fps difference, or 2.8%. That equates to 1.7 grains more of the new lot of powder to achieve the same velocity as the old lot.

Pretty significant IMO. Probably at least partially a result of the old batch having sat around, been opened over and over, and potentially having lost a little volatile weight.

Gonna go ahead and mix the old and new together in the 8lb jug, and of course, rework any H1000 loads going forward.

Anyway, just a little reminder to never take anything for granted. With that sorta variation possible, it's not hard to see how a load could go out of tune. Perhaps more importantly, if you're like me and run up near the top end, you could find unwanted primers in your action just from switching lots. It's one of the reasons why load manuals say "drop it down X% and work up". It's also not uncommon for a lot of powder to change over time, even when stored properly, so I always monitor velocity and pressure through the course of a big jug, and adjust accordingly.
 
I am new to reloading, and with trying to learn everything there is to making a safe and repeatable load, it sure is easy to miss details like this. I sure appreciate you guys throwing this stuff out there. I am a better, more accurate shooter because of you guys!
 
I have run into the same thing with older lots of of partially filled containers of power, particularly the slow burners from Hodgdon like H1000, and Retumbo. Not only do the velocities increase, but I have also seen increases in ES. Keeping the powder in a temperature/humidity controlled safe seems to avoid degradation, and I have had these powders remain consistent for +5 years. For high precision/LRH work I avoid mixing powders that fall out of the original range with a new lot. The averaging/re-adjusting of velocity isn't so much a concern as is the possibility of effecting ES or temperature stability.
 
Thought I would update regarding the mixing...

Shot again today, 4 Old, 4 New, and 5 Mixed. Same 61.0 grain load for all.

Old = 3036 fps
New = 2953 fps
Mixed = 2982 fps


Pretty cool huh? 😁

Why is that cool? I mixed 2.8 lbs of old powder with 4.8 lbs of new powder. So linear mixing model would predict...

((2.8 lbs Old x 3036 fps) + (4.8 lbs New x 2953 fps)) ÷ (7.6 lbs Total) = 2983 fps

So it appears that mixing two lots, at least for the same powder, will produce a velocity that is on a mixing line between the two. Pretty cool.

To summarize for those aren't comfortable with forum formatted algebra

1) Measure the velocity of the old lot, and the weight of powder you have left.
2) Do the same for the new lot.
3) Multiply Old Velocity x Old Weight
4) Multiply New Velocity x New Weight
5) Add 3 and 4 together
6) Divide that by total weight of your Mixed Lot and that should get you relatively close to the new Mixed Lot velocity.

DISCLAIMER! This seems to be valid for the same powder in good condition. It is highly unlikely, and potentially dangerous, to apply this to different types of powder. Mixing a couple of pounds of Retumbo and a few tablespoons Red Dot will almost certainly not get you some of that H4350 you've been dying to find...😳
 
Last edited:
entoptics said:
Thought I would update regarding the mixing...

Shot again today, 4 Old, 4 New, and 5 Mixed. Same 61.0 grain load for all.

Old = 3036 fps
New = 2953 fps
Mixed = 2982 fps


Pretty cool huh? 😁

Why is that cool? I mixed 2.8 lbs of old powder with 4.8 lbs of new powder. So linear mixing model would predict...

((2.8 lbs Old x 3036 fps) + (4.8 lbs New x 2953 fps)) ÷ (7.6 lbs Total) = 2983 fps

So it appears that mixing two lots, at least for the same powder, will produce a velocity that is on a mixing line between the two. Pretty cool.

To summarize for those aren't comfortable with forum formatted algebra

1) Measure the velocity of the old lot, and the weight of powder you have left.
2) Do the same for the new lot.
3) Multiply Old Velocity x Old Weight
4) Multiply New Velocity x New Weight
5) Add 4 and 5 together
6) Divide that by total weight of your Mixed Lot and that should get you relatively close to the new Mixed Lot velocity.

DISCLAIMER! This seems to be valid for the same powder in good condition. It is highly unlikely, and potentially dangerous, to apply this to different types of powder. Mixing a couple of pounds of Retumbo and a few tablespoons Red Dot will almost certainly not get you some of that H4350 you've been dying to find...😳
Click to expand...
Yes, it is pretty cool! But I think there is a question that remains. While the velocities will a average out by weight percentage, how is the ES(extreme spread of velocity) effected. In your example, if each powder had a
20FPS ES…..Old lot/ 3036 +/- 10FPS: New lot/2953 +/- 10FPS……..Would the mixture then have a greater extreme spread? The mixture contains powder that possesses characteristics that could also distribute ES proportionately(or not), resulting in ES that could range from a low velocity of 2943 to 3046, almost 100FPS. While the mixture of two lots may not translate the ES to 100ES, it may also not translate it to the original 20ES of each lot of powder. But if it was even half this amount, it would effect the long range performance. Of course this effect would likely go un-noticed in short to medium range work. The powder manufacturers could probably answer this question. Some have stated over the years that powder lots should not be mixed. I only ask it for a couple of reasons. When I have mixed powders over the years, I have noticed greater ES on occasion, but couldn't be certain it was due to mixing. Secondly, I worked in the chemical/synthesis industry for 45 years where lot blending was used to control the chemical and physical characteristics of the products. This had its limits. There were certain characteristics that were not proportionate as a result of blending, and the blending of different lots could negatively effect the end results.
 
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Just another reason why I'm not a fan of people running loads to the nuts. The load they built might good with one lot then go to another lot and viola it's 100 fps and one is well over pressure....

This should be titled different speeds for different lots, I don't believe it has anything to do with the age of lots. Not at all uncommon to find 100 fps diff between lots!
 
That is getting as high as I have ever seen in the Hodgdon Extreme powders, around 3%. Usually I see less than 2% for sure, .5-1.5% has been common in H4350, Varget etc. When I start a new lot I reduce by 3% and load in increments up to 3% over the old lot, shoot over the chrono and when the velocity matches I have my load. Pull the rest down and done.
 
entoptics said:
Thought I'd throw this out there as a friendly reminder, as well as some actual data to demonstrate what most of us already know.

Got 5 lbs of H1000 a couple months ago, and finally got out to test it against the remainders of an 8lb jug I bought a couple years ago.

Used the exact same 264 Win Mag load for both, loaded together in one session, and shot together in the same gun/session...

60.99 grains
129 gr SST
Fire forming new Winchester brass, bullet jammed ~0.020

New Lot
2965 fps

Old lot
3049 fps

That's an 84 fps difference, or 2.8%. That equates to 1.7 grains more of the new lot of powder to achieve the same velocity as the old lot.

Pretty significant IMO. Probably at least partially a result of the old batch having sat around, been opened over and over, and potentially having lost a little volatile weight.

Gonna go ahead and mix the old and new together in the 8lb jug, and of course, rework any H1000 loads going forward.

Anyway, just a little reminder to never take anything for granted. With that sorta variation possible, it's not hard to see how a load could go out of tune. Perhaps more importantly, if you're like me and run up near the top end, you could find unwanted primers in your action just from switching lots. It's one of the reasons why load manuals say "drop it down X% and work up". It's also not uncommon for a lot of powder to change over time, even when stored properly, so I always monitor velocity and pressure through the course of a big jug, and adjust accordingly.
Click to expand...
I found the same results almost EXACTLY as you. My old lot was almost 75fps faster in my 7mm mag using 160partitions. I have to work up again.
 
I did a comparison yesterday with my 1997 RL 22 vs my new RL 22 in my 7mm Rem Mag. I also compared primers as well.

Old RL22
66.5 Magnum 3170
66.5 Gold 3184
66.7 Magnum 3170
66.7 Gold 3161
67 Magnum 3177

New RL22

66.5 Gold 3118
66.5 Magnum 3119
66.7 Gold 3135
66.7 Magnum 3160
67 Gold 3146
 

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